IL23R and ankylosing spondylitis: Genome-wide association studies performed in the axial and more severe form (i.e., ankylosing spondylitis [AS]) have revealed significant genetic associations with several polymorphisms involved in the T helper 17 cell (Th17) pathway: IL-23 receptor (IL-23R), IL-12B, IL-1R2, IL-6R, and RUNX3.